The invention relates to a disk brake, particularly for commercial vehicles, having a caliper reaching over a brake disk, a brake application device arranged in the caliper for the application of brake pads on both sides of the brake disk in the direction of the disk, as well as at least one adjusting system arranged in the caliper for compensating brake pad and/or disk wear by adjusting the distance between the brake pad and the brake disk. The adjusting system preferably has an adjuster device, particularly a rotary device. The application device arranged in the caliper has at least one rotary lever operable preferably by a rod, particularly a piston rod.
The invention particularly relates to novel constructions of disk brakes, particularly for commercial vehicles, which are actuated pneumatically and/or electromechanically.
According to the principle selected for introducing power, disk brakes can be divided into two basic designs:
1. The generation of power and the wear adjustment on both sides of the brake disk; for example, a hydraulic fixed caliper disk brake with a fixed brake disk relative to the axle, and the generation of power on both sides of the brake disk, and
2. the generation of power and the wear adjustment on one side of the brake disk and the transmission of the actuating power to the side which faces away, according to the reaction power principle; for example, a sliding caliper disk brake, a hinged caliper disk brake, or a fixed caliper disk brake with a slidable brake disk.
Pneumatically actuated disk brakes for heavy commercial vehicles with rim diameters of 15 inches or more normally use the reaction power principle because, as a result of the narrow installation conditions at the vehicle wheel, the arrangement of a pneumatic operating cylinder is only possible on the vehicle interior side of the wheel open toward the vehicle interior. Constructions of these types are shown, for example, in German Patent Document DE 36 10 569 A1, German Patent Document DE 37 16 202 A1, European Patent Document EP 0 531 321 A1 (see particularly the construction of the adjusters along the lines of rotary drives) and European Patent Document EP 0 688 404 A1.
Sliding caliper or hinged caliper disk brakes require a component which is fixed with respect to the axle—generally called a brake anchor plate (carrier)—which holds or guides the brake shoes/brake pads and, when the brake is actuated, absorbs their peripheral forces and carries the caliper which is slidably disposed coaxially to the vehicle axle.
The relative motion carried out by the caliper with respect to the component fixed relative to the axle can be divided into the working stroke and the wearing stroke. The invention makes surprising use of this effect.
The working stroke is carried out with each actuation of the brake in order to overcome the release play of the brake and to compensate for the elasticities of the brake pads and the caliper that result from the application of power. Depending on the extent of the actuating power and the amount of the release play, it is normally <4 mm.
In contrast, the wearing stroke is the wear adjusting travel which the caliper carries out over a large number of brake actuations in order to compensate for the wear on the reaction side of the brake. The wearing stroke is composed of the wear of the outside brake pad and the wear of the brake disk friction surfaces situated on the outside, and normally amounts to up to 25 mm.
In comparison, in the case of the brake design with a fixed caliper and a slidable brake disk, the working stroke and the wearing stroke are generated by sliding the brake disk.
The designs with the sliding caliper or hinged caliper have the disadvantage that the brake anchor plate, fixed relative to the axle, is required for absorbing the peripheral force of the brake pads and the holding and guiding of the caliper. This component results in additional cost and additional weight. Furthermore, the required sliding guidance or hinge system is susceptible to problems.
In the design with the slidable brake disk, in contrast, the problem is in maintaining easy slideability of the brake disk on the guiding area of the hub throughout the entire service life. An effective sealing-off can hardly be implemented because of the narrow installation conditions and the harsh environmental exposure.
It is known (for example, from European Patent Document EP 0 531 321) to provide the rotary lever 19 with an eccentric or eccentric section, which acts directly or by way of additional elements upon a traverse (cross-member) into which the thrust pieces are screwed.
It is also known to provide the rotary lever with lateral projections, which act upon the ends of the thrust pieces or on adjusting sleeves into which the thrust pieces are screwed (German Patent Document DE 36 10 569 A1).
Both concepts for the construction of the rotary lever are utilized. The lever has an approximately semicircular projection which, on the outer diameter, forms the slide-way for a roller bearing, in the interior of the respective semicircular projection, the eccentric is formed by means of a slide bearing half shell as well as a bearing roller accommodated therein.
Particularly in the case of the second described construction, this bearing arrangement makes it possible to keep the reaction forces of the eccentric bearing and of the outer roller bearing congruent in their position on the longitudinal axis of the lever.
As a result, it is possible to avoid bending stress or deformations on the lever as well as the resulting edge movement of the roller bearing and the slide bearing, which may clearly reduce the service life of the bearings.
Although in the case of the construction having a traverse, the deformation of the lever is reduced by means of the traverse, here also an increase of the service life is desirable, particularly by avoiding an edge movement.
A replacement of the roller bearing is also desirable on the side of the larger diameter of the eccentric projection of the rotary lever. The necessity to arrange the outer bearing shell as a semi-cylindrical projection in an enveloping manner around the eccentric necessarily leads to relatively large bearing diameters of the outer bearing. This results in the necessity of using a roller bearing on the outer bearing since, when a slide bearing is used, the higher resistances to friction in conjunction with the large friction diameters may lead to friction losses and application force losses and, as a result, to an undesirably high brake hysteresis.
With respect to eccentric-operated disk brakes, it should be mentioned that the prior art also includes German Patent Document DE 44 30 258 C1, International Patent Document WO97/22814 and German Patent Document DE 295 08 001 U1.
The disk brake of the construction of this type, particularly its brake application device, is to be optimized in that an extensive use of slide bearings with small friction diameters is achieved while the deformations of the rotary lever are simultaneously minimized.
The invention achieves this task by means of the claimed objects.
According to the invention, the construction of the brake application device per se is particularly simplified. The invention is suitable for calipers of many different constructions, such as sliding and hinged calipers but also for fixed calipers or (micro)-deformable calipers.
Accordingly, the rotary lever has a recess for receiving the end of the piston rod on one of its ends, and has recesses on its end area facing away from the recess on two of its exterior sides, into which recesses essentially cup-shaped bearing shells and/or essentially spherical bearing elements for bearing the rotary lever can be inserted, by means of which the rotary lever is disposed on the caliper and on at least one thrust piece for displacing the brake pad in the direction of the brake disk.
The rotary lever is thereby constructed as a traverse-type structural member, which makes the use of a traverse (cross-member) separate from the rotary lever unnecessary. The spherical bearing elements, which can be disposed in the slide bearing shells permit a durable stable bearing of the rotary lever and an overall compact cost-effective construction of the brake application device.
In a constructively simple manner, the rotary lever is directly, or by way of additional intermediately connected elements, disposed on the caliper—lever bearing—and directly, or by way of additional intermediately connected elements, disposed on the at least one thrust piece—eccentric bearing—.
The bearing shells are expediently constructed at reasonable cost as slide bearing shells.
Advantageously, the spherical bearing elements are arranged on the traverse-shaped section of the rotary lever on opposite sides with an opposed pressure direction.
Particularly preferably, the spherical bearing elements are arranged with their ball centers in the longitudinal direction of the traverse-type section—and thus perpendicular to the lever arm A—A—parallel to the brake disk as well as transversely to this longitudinal direction in a mutually spaced manner.
Advantageously, the mutually opposite spherical bearing elements or bearing balls of the lever and eccentric bearings are each arranged in the traverse-type section of the rotary lever such that the ball centers are situated almost or completely on a connection plane with the pivot of the operation on the lever arm. In particular, a compact arrangement of the ball elements of the bearing of the rotary lever is achieved thereby.
Expediently, the position of the eccentric bearing for achieving a defined change of the transmission ratio as a function of the lever position is offset by a given amount from the connection plane of the center of the lever operation to the lever bearing centers.
The slide bearing shells are preferably arranged in the rotary lever, or in the part of the caliper or the intermediate pieces which face away in each case, or on both sides of the spherical bearing elements or bearing balls, so that the bearing of the rotary lever takes place exclusively via slide bearings and bearing balls inserted into the slide bearings.
The lever cup advantageously has a toroidal shape.
Advantageously, the lever cup has a larger cup diameter in the swivelling direction than transversely to this swivelling direction.
When the brake is designed with, in each case, only one thrust piece or only one adjusting rotary drive on one or both sides of the brake disk, the rotary lever is advantageously and constructively favorably provided with two lever bearings at the ends of the traverse-type section and with only one eccentric bearing in the center.
Preferably, the essentially spherical bearing elements and their receiving devices have mutually corresponding devices for protecting against torsion, which devices are constructed as a butt-welded or friction-welded seat or, for example, as a dowel pin or spring dowel sleeve.
Expediently, the essentially spherical bearing elements and their receiving devices have, as a device for protecting against torsion, on their sides pointing toward one another, mutually corresponding torsion-proof geometrical shapes or, on their sides pointing toward one another, mutually corresponding flattenings and/or indentations and projections.
The indentations/projections expediently have concave/convex or ball-cup-shaped constructions.
Preferably, in each case, at least one of the adjuster rotary devices is provided on each side of the brake disk for adjusting the axial distances between the two brake pads and the brake disk.
Furthermore, preferably the generating of the reaction power on the side of the brake facing away from the application side is carried out by                the sliding of the caliper and/or        the swivelling of the caliper and/or        the sliding of the brake disk.        
In each case, as the result of the sliding and/or swivelling motion, essentially only the length of the power stroke can be bridged.
The invention combines the advantages of the fixed-caliper principle—such as compact construction and implementation of the wearing stroke by the actuating system—with the advantages of the reaction power principle.
As a result of the additional adjusting device(s) on both sides of the disk brake, it is permitted to further develop the brake such that only a mobility, preferably a slidability and/or a swivellability of the caliper and/or the brake disk have to be ensured, which is dimensioned such that the working stroke during brakings can be bridged in order to apply the brake. In this manner, the sliding and/or rotary bearings and guides can be dimensioned to be correspondingly smaller and less expensive. Additionally, it is ensured that a smooth running takes place along the complete sliding or swivelling path since the latter is bridged during virtually every braking.
The brake disk is preferably constructed as a sliding disk which is slidably guided on a brake disk hub such that, as a result of the sliding, (only) a sliding path can be implemented which is limited to the power stroke.
As an alternative or in addition, the caliper can be constructed as a sliding caliper, which has a sliding caliper bearing which can be fastened directly to the axle flange and which is dimensioned such that (only) a sliding path can be bridged which is limited to the power stroke.
As an alternative or in addition, the caliper may be constructed as a hinged caliper which has a hinged caliper bearing, which preferably can be fastened directly to the axle flange and can be bridged by means of the swivelling angle which displaces the caliper relative to the brake disk essentially by the amount of the power stroke.
In particular, the disk brake according to the invention makes it possible to continue to arrange the power generating device—such as a pneumatically actuated and/or electric-motor-actuated brake cylinder or an electric drive—only on one side on the brake.
Additional advantages are achieved within the scope of the invention.
A variant, which—can also be considered independently,—of the invention solves the problem of the joint adjustment of the adjustable rotary drives on both sides of the disk brake. Here, the adjustable rotary drives on both sides of the brake disk are mutually coupled by means of a synchronizing device. The synchronizing device is preferably constructed as a coupling mechanism or as an electronic coupling system.
According to another variant, which—can also be considered independently,—of the invention, the adjusting system itself is further improved. This variant, in the case of which a particularly space-saving adjusting module is created, which can be produced particularly economically, is suitable for brakes of a conventional construction as well as for brakes of the type claimed.
According to another claim, the adjusting system on one or both sides of the brake disk is constructed as an adjuster module, which can be preassembled and which has at least                preferably an electric motor as the drive,        a reduction gear connected behind the electric motor,        which can be mounted jointly on a mounting preform, particularly a mounting plate or preferably between two mutually spaced mounting preforms, and        wherein the rotary drive(s) are inserted on/in the at least one mounting preform(s).        